Model Mouse Designed for Oral Biofilm Formation Studies

Abstract

To study biofilm formation on artificial in vitro environments does not lead to understanding the natural mechanism of biofilm formation on the teeth surfaces because artificial surfaces differ physically and environmentally from teeth surfaces. Therefore, an animal model is required to study biofilm formation ; however, there has not been a good in vivo model previously reported. Recently, a high susceptibility model mouse : C57BL/6.E2f1^-/- mice were found. In our studies using genetic recombination and target gene mutations, NOD.B10D2, NOD.E2f1^-/- and NOD/SCID.E2f1^-/- mice were constructed using a NOD background gene base and AQP deficient mice were also established. Non-obese diabetic (NOD) mouse is an established model for human-dependent diabetes mellitus (IDDM) and Sjögren's syndrome (SS). All recombinant and mutant mice showed a decreased saliva phenotype in comparison to control mice. The volume of saliva produced was higher in NOD.B10D2 mice than in the other mutant mice. The lifespan of NOD.E2f1^-/- mice was shorter than NOD/SCID.E2f1^-/-, C57BL/6.E2f1^-/- mice and AQP^-/- mice because NOD.E2f1^-/- showed a more progressive development to IDDM and SS than did NOD mice. Therefore, NOD.E2f1^-/- mice were not suitable for long-term bacterial infection experiments. NOD/SCID.E2f1^-/- ; did not show diabetes or insulitis ; and AQP^-/- mice showed a decreased volume in saliva and showed an increased susceptibility to oral infections. Therefore, we consider NOD/SCID.E2f1^-/-, C57BL/6.E2f1^-/- mice and AQP^-/- mice may be useful animal models for initial adhesion and biofilm formation to study oral streotococci infections and dental caries.